Short-term Investments (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Sep. 30, 2014
Schedule Of Available For Sale Securities [Line Items]
Short-term Investments, Amortized Cost	$ 19,629	$ 19,900
Short-term Investments, Unrealized Losses	(19)	(39)
Short-term Investments, Estimated Fair Value	19,610	19,861
Corporate
Schedule Of Available For Sale Securities [Line Items]
Short-term Investments, Amortized Cost	16,170	14,262
Short-term Investments, Unrealized Losses	(18)	(27)
Short-term Investments, Estimated Fair Value	16,152	14,235
Government
Schedule Of Available For Sale Securities [Line Items]
Short-term Investments, Amortized Cost	3,459	5,638
Short-term Investments, Unrealized Losses	(1)	(12)
Short-term Investments, Estimated Fair Value	$ 3,458	$ 5,626